It looks like a bucket list for city trips, but it’s the current route of the HALO research aircraft. Until the end of July, atmosphere researchers from all over Germany will study air pollution above European conurbations. They want to better understand and predict the impacts of pollution on the Earth’s atmosphere. Two instruments on board HALO have been developed by researchers of Karlsruhe Institute of Technology (KIT) to measure concentrations of ozone and volatile hydrocarbons.